Implemented definitions

src/build/Variable.go

@@ -2,11 +2,18 @@ package build
 
 import (
 	"git.akyoto.dev/cli/q/src/build/cpu"
+	"git.akyoto.dev/cli/q/src/build/expression"
 )
 
-// Variable represents a variable in a function.
+// Variable represents a named register.
 type Variable struct {
 	Name     string
 	Register cpu.Register
 	Alive    int
 }
+
+// Definitions are single use expressions that don't reside in a register yet.
+type Definition struct {
+	Name  string
+	Value *expression.Expression
+}